<!DOCTYPE html>
<html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
        <style>
        div{
            background-color:saddlebrown;
            color: powderblue;
            width: 100px;
            transition:background-color 1s linear,color 1s linear,width 1s linear;
        }
        div:hover{
            background-color: crimson;
            color: currentColor;
            width: 200px;

        }
        </style>

    </head>
    <body>
        <div>实例</div>

    </body>
</html>